Electrical connector for use in an experimental circuit kit



R. R. LEWIS 3,093,431

ELECTRICAL CONNECTOR FOR USE IN AN EXPERIMENTAL amour: KIT

June 11, 1963 Filed Oct. 11, 1961 R m N w W.

RICHARD R. LEWIS ATTORNEYS United States Patent 3,093,431 ELECTRICALCONNECTOR FOR USE IN AN EXPERIMENTAL CIRCUIT KIT Richard R. Lewis, 23Lawrence St., Cambridge, Mass. Filed Oct. 11, 1961, Ser. No. 144,339 2Claims. (Cl. 339-18) This invention relates to electrical connectors,and more particularly to an improved electrical connector for use in anexperimental kit for constructing electrical or electronic circuits foreducational purposes.

For teaching electrical theory with the aid of experimental circuitry,it is desirable to afford means for simply and conveniently makingelectrical connections between leads and components without the use ofsolder or tools, so that modifications in a circuit may readily be made,or a series of different circuits rapidly constructed. At the same time,it is necessary that connections of good conductivity be established bythese means. It is also desirable to afiord some form of base upon whichthe circuit components may be mechanically supported without the use oftools or complex, time-consuming mounting procedures. To minimize thenumber and variety of components in the kit, this support is preferablyobtained by means of the connectors themselves.

It is accordingly the primary object of this invention to provide animproved electrical connector to which a plurality of leads orcomponents may be quickly connected in good conductive relation withoutthe use of tools, solder, or fasteners. It is a further object of theinvention to afford an improved connector which cooperates with a basemember to mechanically support circuit components connected thereto.Further objects and advantages of the invention will become apparent asthe following description proceeds.

Briefly stated, the invention is preferably embodied in a connectorhaving a conductive helical coil spring, an insulating mounting plugsecured within one end of the spring, and an insulating cap orreceptacle secured on the other end of the spring. The coil spring isreadily expandable to receive wires or component leads in secureengagement between the turns thereof, for electrical connection as wellas mechanical support. I prefer to form the spring of copper orcopper-plated spring stock, and may also provide a gold flashing on thesurfaces of the turns for maximum conductivity. The number of componentsor leads which may be connected by a single connector is limited only bythe number of turns of the coil.

The insulating cap is formed of vinyl, nylon, or other suitableinsulating material, and serves not only to protect the user againstshock, but also affords a receptacle for the insertion of a banana plugconnector axially into the interior of the coil, for connection of testinstruments or other devices which are normally equipped with this typeof plug.

According to a further feature of the invention, the mounting plug isformed of resilient insulating material and terminates in a splitdeformable portion for convenient mechanical mounting of the connectorby insertion of the plug through a suitably formed opening of a pegboard or other mounting base. Further, I prefer to form the plug with acircumferential locating flange for abutment against the peg board tosupport and locate the connector and the components connected thereto ina secure manner. By these means, a circuit may be arranged securely onthe peg board or other base without the use of additional mounting orfastening means. To disassemble the circuit, the leads and componentsare merely pulled from the spring, and the connector plugs are manuallyextracted from the peg board. The plug and cap are preferably securedfirmly to the ends of the spring by means of epoxy resin or otheradhesive, although they might alternatively be threaded resiliently uponthe turns of the spring.

While the specification concludes with claims particularly pointing outthe subject matter which I regard as my invention, it is believed that aclearer understanding may be obtained from the following detaileddescription of a preferred embodiment thereof, referring to theaccompanying drawing, in which:

FIG. 1 is a pictorial view of the improved connector;

FIG. 2 is a pictorial view as seen from below the connector;

FIG. 3 is a cross-sectional view, showing the connector assembled in apeg board or mounting base;

FIG. 4 is a fragmentary pictorial view showing the method of connectinga banana plug in the receptacle or cap of the connector; and

FIG. 5 is a pictorial view showing the method of connection of leads andcomponents to the connector.

Referring to the drawings, the improved connector includes a conductivehelical coil spring 10, which is preferably formed of a resilient buthighly conductive material or composite of materials. I prefer to formthis member of spring steel, copper plated and gold flashed, for maximumsurface conductivity.

An insulating cap or receptacle 12 is formed with a cylindrical opening14 to receive the upper end of the spring therein. I prefer to form thecap 12 of vinyl or other readily moldable plastic material, but anydesired insulating material may be utilized. The insulating cap, beingresilient, may be threaded on the spring 10, but is preferably securedto the spring by means of a layer of epoxy resin or other adhesivematerial 16, for maximum resistance to accidental separation when thecap is pulled by a user to disassemble the connector from a mountingboard.

An insulating mounting plug 18, formed of a resilient material similarto that of the cap '12, has a cylindrical portion 20 which is snuglyreceived in the lower end of the spring. Again, the portion 20 may bethreaded into the spring, but I prefer to apply a layer of adhesive 22to strengthen the assembly. The plug is formed with a circumferentiallocating flange 24, and with a split deformable portion 26 for insertioninto one of a plurality of openings 28 of a conventional peg board 30 orother desired mounting base. It will be apparent that the connector canbe quickly plugged into or removed from the base, but that the splitportion expands to its original configuration when the plug is inserted,as shown in FIG. 3, to hold the connector securely in place and providefirm support for circuit components mounted thereon.

As shown in FIG. 4, the opening 14 of the cap 12 is arranged to receivea banana plug 32 of a lead 3'4, such as is commonly used to connectinstruments and other electrical devices for experimental or testpurposes. The plug enters the interior of the coil spring to makeelectrical contact therewith. Referring to FIG. 5, the method ofconnecting an illustrative series of leads and components 35, 36, and 37is shown. The user has only to apply tension to the cap, oralternatively to bend the spring to one side, for convenient insertionof the leads between the parted turns of the spring.

By utilizing a plurality of the improved connectors in combination witha suitable peg board, an educational or experimental circuit kit may beafforded which requires no solder, tools, or additional fasteners forthe rapid construction and electrical connection of any desired oircuit.A circuit once constructed can be quite readily modified ordisassembled, simply by withdrawing the leads and banana plugs from theconnectors, after which the connectors may be pulled from the peg board.

Various changes and modifications will readily occur to those skilled inthe art without departing from the true spirit and scope of theinvention; I therefore intend to define the invention in the appendedclaims without limitation to specific details of the preferredembodiment herein described by way of illustration.

What I claim is:

1. An electrical connector adapted for use in constructing experimentalcircuits 'upon a mounting base having a plurality of openings formedtherein, said connector comprising a conductive helical coil spring, aninsulating cap having a cylindrical opening therethrough, one end ofsaid spring being secured in said cylindrical opening for insertion of aplug connector therethrough into contact with the interior of saidspring, and an insulating plug secured to the other end of said springand having a split portion resiliently deformable upon insertion into anopening of said mounting base for supporting said connector, said plugbeing formed with a locating flange extending circumferentiallythereabout for abutment upon said mounting base about said openingtherein.

2. A kit for constructing experimental electrical circuits, comprising amounting board formed with a plurality of spaced openings, and aplurality of electrical connectors each including an insulating plughaving a split resiliently-deformable portion for insertion into one ofsaid openings to mount said connector on said board, each of saidconnectors further including a conductive helical coil spring secured atone end thereof on said plug, and an insulating cap secured to the otherend of said spring, said insulating cap being formed with a cylindricalopening for insertion of a plug connector therethrough into contact withthe interior of said spring.

References Cited in the file of this patent OTHER REFERENCES ElectronicDesign, March 18, 1959, pages 152, 153.

25 Article entitled, Ideas for Design, by Walter F. Dimmik.

2. A KIT FOR CONSTRUCTING EXPERIMENTAL ELECTRICAL CIRCUITS, COMPRISING AMOUNTING BOARD FORMED WITH A PLURALITY OF SPACED OPENINGS, AND APLURALITY OF ELECTRICAL CON-